NetSpectre: Read Arbitrary Memory over Network

Summary

All Spectre attacks so far required local code execution. We present the first fully remote Spectre attack. For this purpose, we demonstrate the first access-driven remote Evict+Reload cache attack over the network, leaking 15 bits per hour. We present a novel high-performance AVX-based covert channel that we use in our cache-free Spectre attack. We show that in particular remote Spectre attacks perform significantly better with the AVX-based covert channel, leaking 60 bits per hour from the target system. We demonstrate practical NetSpectre attacks on the Google cloud, remotely leaking data and remotely breaking ASLR.